CAIRO, GENEVA —
The Syrian army says it will suspend military operations to mark the Muslim holiday of Eid al-Adha, declaring a cease-fire from Friday morning to Monday. The army added that it reserves the right to respond to rebel attacks and bombings.

In an announcement read on state TV late Thursday, the Syrian military said it will act if "terrorist groups [are] trying to reinforce their positions by arming themselves and getting reinforcements."

It also warned neighboring countries against facilitating the smuggling of fighters across borders during that period.

A commander for the rebel Free Syrian Army said his fighters would commit to the truce, but would respond to any attacks.

Both sides have violated previous cease-fires after agreeing to them. However, an Islamist group active in Syria, Ansar al-Islam, is reported to have said that its fighters will not commit to the truce.

Timeline of Syria Uprising

March 2011: First protests erupt, dozens killed. Government announces reforms, then resigns.

April, May 2011: Protests intensify and spread, hundreds killed. U.S. imposes sanctions on top leaders.

July 2012: Red Cross expands areas of Syria it says are in civil war. Violence increases across the country.

August 2012: A day after Syrian warplanes attacked the rebel-controlled northern town of Azaz and a bombing near the U.N. observer headquarters in Damascus, the U.N. Security Council decides to end the U.N. monitoring mission in Syria when its mandate expires on August 19. Annan steps down as U.N.-Arab League envoy to Syria.

September 2012: Fighting intensifies in Aleppo and continues across the country. New U.N.-Arab League envoy Lakhdar Brahimi visits the country and meets with Assad.

October 2012: Aleppo's historic souk burns as fighting rages in the city. The Syrian army says it will suspend military operations to mark the Muslim holiday Eid al-Adha, declaring a cease-fire during the holiday, but reserving the right to respond to rebel attacks and bombings.

UN hails cease-fire

In New York, United Nations spokesman Martin Nesirky said the world body welcomed the cease-fire.

"Obviously, the world is now watching to see what will happen on Friday morning," he said. "It’s in everybody’s interest, not least the long suffering Syrian people, that the guns fall silent tomorrow morning for the Eid holiday."

Rebel commanders in various cities told Arab satellite channels that they would respect the cease-fire if the government did.

But one Free Syrian Army officer said, however, that the cease-fire was contingent on the government's releasing prisoners and lifting the blockade of Homs.

More battles

The cease-fire announcement came after reports that the rebels had made significant advances in Syria's northern commercial hub of Aleppo. Government forces were reported to have pulled out of one Kurdish and two Christian districts inside the city.

The reports could not be confirmed and the Syrian government did not comment.

Syria scholar Joshua Landis, who heads the Center of Middle Eastern Studies at the University of Oklahoma and has been monitoring reports coming from Aleppo, said government forces appear mired in a fluid battle with rebels.

"The government has been flailing about in Aleppo for the last several weeks, bombing neighborhoods where it can't send men in," he said. "It doesn't have the manpower to overtake the city and by some estimates — pretty well-educated estimates — there are about 70,000 rebel troops in Aleppo and the regime just cannot hang on. They just don't have the manpower.”

Rebel commander Abdel Jaber al Okeidi told al Arabiya TV that the government had used field artillery throughout Thursday, across much of Aleppo. Other witnesses reported that heavy rains prevented government forces from bombing the city.

Government forces are reported to have remained in control of Aleppo's airport in the southeast of the city. But rebels appear to control a military airport to the west.

Elsewhere, amateur videos posted on the Internet showed Syrian government troops and tanks pulling out of parts of what appeared to be the southern city of Daraa. Heavy government shelling was also reported in the rebel stronghold of Harasta, outside Damascus.

UN rights demands

In Geneva, meanwhile, United Nations investigators said they have sent a letter to Syrian President Bashar al-Assad, asking for a meeting regarding the deteriorating human rights situation in Syria.

It is the first time the U.N. Commission of Inquiry on Syria has asked for a face-to-face meeting with the Syrian president. The Syrian government has refused to grant access to the commission during its previous fact-finding missions.

Given the intensified fighting and worsening human rights situation in Syria, the commission chairman, Paulo Pinheiro, said he hopes that he and his colleagues can meet with Assad.

"We do not have a crystal," he said. "I do not know if he will accept us. But, it was our duty to have access."

An investigators' report presented to the U.N. Human Rights Council in August accused both the Syrian government and opposition forces of war crimes and crimes against humanity.

The report blames the highest levels of the government, as well as security and armed forces for committing atrocities including murder, torture, attacks against civilians and acts of sexual violence.

While the investigators say opposition forces also have committed war crimes, they say these violations and abuses are not of the same gravity, frequency and scale as those committed by the government and its allies.

The U.N. Human Rights Council extended the mandate of the commission at the end of September, increased the number of investigators to four, and provided more money and people to support its work.

As part of its investigation, the commission says it will determine which high-ranking Syrian political and military figures are responsible for crimes in Syria.

Investigators say it will be up to the U.N. Security Council to decide when and if the list should be made public.

A support team will be going to the Mideast in the coming weeks to lay the groundwork for the commission's fact-finding mission. The group plans to complete a report on its findings in January and submit it to the U.N. Human Rights Council in March.